diff --git a/synapse/api/constants.py b/synapse/api/constants.py
index 84cbe710b..8cf4d6169 100644
--- a/synapse/api/constants.py
+++ b/synapse/api/constants.py
@@ -32,7 +32,6 @@ class PresenceState(object):
     OFFLINE = u"offline"
     UNAVAILABLE = u"unavailable"
     ONLINE = u"online"
-    FREE_FOR_CHAT = u"free_for_chat"
 
 
 class JoinRules(object):
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index 1942e2ad3..439bfe591 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -606,6 +606,12 @@ class PresenceHandler(BaseHandler):
         status_msg = state.get("status_msg", None)
         presence = state["presence"]
 
+        valid_presence = (
+            PresenceState.ONLINE, PresenceState.UNAVAILABLE, PresenceState.OFFLINE
+        )
+        if presence not in valid_presence:
+            raise SynapseError(400, "Invalid presence state")
+
         user_id = target_user.to_string()
 
         prev_state = yield self.current_state_for_user(user_id)